ADT7475ARQZ ON Semiconductor, ADT7475ARQZ Datasheet - Page 8

• Manufacturer Part Number: ADT7475ARQZ
• Description: IC REMOTE THERMAL CTRLR 16-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7475ARQZ

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Full Temp Accuracy: +/- 0.5 C
• Digital Output - Bus Interface: Serial (3-Wire, 4-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Product Description
fan controller for any system requiring thermal monitoring
and cooling. The device communicates with the system via
a serial system management bus. The serial bus controller
has a serial data line for reading and writing addresses and
data (Pin 16), and an input line for the serial clock (Pin 1).
All control and programming functions for the ADT7475
are performed over the serial bus. In addition, a pin can be
reconfigured as an SMBALERT output to signal
out−of−limit conditions.
Quick Comparison Between ADT7473 and ADT7475
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powered by a supply no greater than 3.6 V. Exceeding this
Serial Bus Interface
using the SMBus. The ADT7475 is connected to this bus as
a slave device under the control of a master controller, which
is usually (but not necessarily) the ICH.
0101110 or 0x2E. The read/write bit must be added to get the
8−bit address (01011100 or 0x5C). Data is sent over the
serial bus in sequences of nine clock pulses, that is, eight bits
of data followed by an acknowledge bit from the slave
device. Transitions on the data line must occur during the
low period of the clock signal and remain stable during the
The ADT7475 is a complete thermal monitor and multiple
The ADT7475 is similar to the ADT7473 in that it is
On PCs and servers, control of the ADT7475 is carried out
The ADT7475 has a fixed 7−bit serial bus address of
The ADT7473 supports advanced dynamic T
features while the ADT7475 does not.
Acoustic smoothing is improved on the ADT7475.
THERM can be selected as an output only on the
ADT7475.
The ADT7475 has two additional configuration
registers.
The ADT7475 has other minor register changes.
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
Figure 12. ADT7475 Configuration
MIN
http://onsemi.com
TACH2
PWM3
TACH3
D1+
D1–
ADT7475
GND
8
SMBALERT
specification results in irreversible damage to the ADT7475.
Signal pins (TACH/PWM) should be pulled up or clamped
to 3.6 V maximum. See the Specifications Section for more
information.
Recommended Implementation
the system designer to use the following features:
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high period because a low−to−high transition when the clock
is high may be interpreted as a stop signal. The number of
data bytes that can be transmitted over the serial bus in a
single read or write operation is limited only by what the
master and slave devices can handle.
established. In write mode, the master pulls the data line high
during the tenth clock pulse to assert a stop condition.
In read mode, the master device overrides the acknowledge
bit by pulling the data line high during the low period before
the ninth clock pulse; this is known as no acknowledge. The
master takes the data line low during the low period before
THERM
TACH1
PWM1
Configuring the ADT7475 as shown in Figure 12 allows
When all data bytes are read or written, stop conditions are
Two PWM outputs for fan control of up−to−three fans
(the front and rear chassis fans are connected in
parallel).
Three TACH fan speed measurement inputs.
V
CPU temperature measured using the Remote 1
temperature channel.
Ambient temperature measured through the Remote 2
temperature channel.
Bidirectional THERM pin. This feature allows Intel
Pentium 4 PROCHOT monitoring and can function as
an overtemperature THERM output. The THERM pin
can alternatively be programmed as an SMBALERT
system interrupt output.
SDA
SCL
D2+
D2–
CC
measured internally through Pin 3.
PROCHOT
CPU FAN
ICH
CPU